MP4 files are also typically seen when a video is downloaded from the internet. The explosion in popularity of the MP4 format is largely down to Apple and the iTunes Store, as it is the standard format for almost all of the media downloaded from the store. The video part is compressed with MPEG-4, a standard that was developed by Moving Picture Expert Group (MPEG), while the audio is typically compressed using AAC compression. Video and audio compression are usually handled by different codecs (audiovisual encoders).
MP4 files are typically smaller in size than other audio or video file types because MP4 files use a mix of compression technologies. An MP4, sometimes known as an MPEG4, is a multimedia file that is used to store video or audio data.